Electrolytic recording medium containing a phenolic ether



a nea 051x 3? Sept. 12, 1967 M, GRADSTEN ETAL 3,341,431 ELECTROLYTIC RECORDING MEDIUM CONTAINING A PHENOLIC EITHER Filed July 5, 1964 PYROGALLOL -l-ME7'HYL E THER FORMULA 770/V/E'ROD/NG A/VDDE ELECF RODE MARK) USING HE L IX AND BAR RECORDER MIL L M MPERES OPE CAL 0 30 100 150 200 e50 300 MILL IAMPERES 2- (2-HYDROXY-P/-/EA OXY) ETHANOL FORMULATION (EROD/IVG A/VODE ELECTRODE MAR/I) US/A/G HE L I)! AND BAR RECORDER I 5 6' 7 1 E; 5 1: O F/G. 5'

M/LL/AMPERES INVENTORS CURVE SPOT SPEED OF 23 IM/ SEQ MQRGELAGRADSTEW cu/WE 2-3pm .SPEE 0F 45 //v. /sc. WWI/1N6 HEM/3 cum/5 s or SPEED OF I35 //v. s50. 53

United States Patent Filed July 3, 1964, Ser. No. 380,166 19 Claims. (Cl. 204-4) The present invention relates to the art of electrolytic recording, and more particularly to an electrolytic recording medium impregnated with polyhydric phenol ethers. Heretofore, certain polyhydric phenols such as catechol have been discovered to be capable of serving as marking compounds in aqueous electrolytic recording media and recording paper such as disclosed in U.S. Patent No. 2,339,267 to J. V. L. Hogan et a1. and U.S. Patent No. 3,358,839 to E. R. Wagner.

Such papers may be employed in an electrolytic recording apparatus such as described in U.S. Patent No. 2,202,855 to J. V. L. Hogan et al. The base paper is impregnated with an electrolytic solution containing at least one marking compound. Generally, stabilizers and antifringing agents are also added. Although the recording medium is generally paper, it may be any other porous material which is capable of holding the impregnant in an electrolytic medium.

In order to be acceptable as a commercial product the electrolytic recording paper in its unmarked state must be capable of being stored in moist condition in special containers and remain stable without chemical decomposition of its ingredients which would result in discoloration of the paper prior to its use. Further, it is important that the paper resist fading or discoloration after marking.

Heretofore two types of recording paper have been mentioned in the art. The most common electrolytic recording media depend upon the introduction of metal ions into the recording paper so as to interact with the marking compound to form the mark. Such papers may be termed eroding anode electrode marking papers and are exemplified by the catechol papers. In other instances the mark is made without the introduction of metal ions from the anode electrode, in which event the papers may be termed non-eroding anode electrode marking papers and are exemplified by papers such as described in U.S. Patents Nos. 160,404, 166,861, and 168,466 to Edison, U.S. Patent No. 2,570,096 to Calkin, and U.S. Patent No. 3,122,488 to Mandel.

The present invention aims to provide electrolytic recording papers incorporating as marking compounds a class of compounds which heretofore has not been employed for this purpose. All of the compounds in this class are suitable for use as constituents of eroding anode electrode marking media as described above. In addition, a number of the members of this class are suitable for use as constituents of non-eroding anode electrode marking media.

In accordance with the invention it has been discovered that members of the phenolic ether class serve as excellent marking compounds in electrolytic recording paper. Heretofore, the use of phenolic ethers has been mainly in the perfume and in the pharmaceutic fields.

The marking compounds are phenolic ethers having at least one hydroxyl group on the ring and an aliphatic, cycloaliphatic, aromatic or heterocyclic group attached to an ether oxygen. It is preferred that there be present an ortho orientation between the ether oxygen and a hydroxyl group. Usually the orientation of the ether oxygen and a hydroxyl group will be other than metal. The most prehaving one to six carbon atoms, -OH, -OR

ferred compounds constitute the class represented by the following general formula:

where R, R R and R are selected from the group consisting of H, lower aliphatic hydrocarbon groups usually having one to six carbon atoms, OH, --OR (Where R is a lower aliphatic group usually having one to six carbon atoms); where M is selected from the group consisting of aliphatic, cy-cloaliphatic, aromatic and heterocyclic groups, but usually aliphatc groups. Where Water solubility is of interest M and the other groups will be selected to impart water solubility. It is to be understood that the substituent groups may contain functional groups such as hydroxyl, carboxyl, and amines.

The simplest member of this class is guaiacol wherein R, R R and R are H and M is CH Other representative compounds of this class are:

2- (Z-hydroxyphenoxy) ethanol 2,3-dihydroxyphenoxy acetic acid 2,6dihydroxyphenoxy acetic acid 2,3-dihydroxyphenoxy beta propionic acid pyrogallol-Lmethyl ether pyrogallol-2-methyl ether 2,6-dimethoxyphenol pyrogallol-l-(2-hydroxyethyl)ether pyrogallol-Z- 2-hydroxyethyl) ether pyrogallol-l-allyl ether pyrogallol-Z-allyl ether 3methoxy-6-methyl-1,Z-dihydroxy benzene 3-(2,3dihydroxyphenoxy)n-propyl amine (2,6-dihydroxy-3-a1lyl) phenoxyallyl ether 2-(2,3-dihydroxyphenoxy)ethanol 2-methoXy-l,4 dihydroxy benzene It has also been found that certain compounds of the general class are especially suitable for electrolytic marking media which are used in a recorder with a noneroding anode electrode. These compounds can be classified in a sub-class of polyhydric phenol ethers in which at least two of the phenolic hydroxyl groups are ortho or para to each other and which contain at least one ether group vincinal to one hydroxy group. Such compounds are represented by the following general formula:

Where R R, and R are selected from the group consisting of H, lower alphatic hydrocarbon groups usually (where R is a lower alphatic group usually having one to siX carbon atoms); where M is selected from the group consisting of aliphatic, cycloaliphatic, aromatic and heterocyclic groups, but usually aliphatic groups. Where water solubility is of interest M and the other groups will be selected to impart water solubility. It is to be understood that the substituent groups may contain functional groups such as hydroxyl, carboxyl, and amines.

Representative members of the subclass of marking compounds which mark with a non-eroding anode electrode are:

pyrogallol-l-methyl ether pyrogallol-l-allyl ether 3-methoxy-6-methyl-1,2-dihydroxy benzene 2- 2,3-dihydroxyphenoxy) ethanol 2-methoxy-1,4-dihydroxy benzene Preferred formulations to impregnate about 1000 square feet of white porous paper are set out hereinafter. The impregnated paper is electrolytically markable upon passage of a direct current therethrough, the current being applied between the electrodes of recording apparatus such as described in the Hogan et al. Patent No. 2,202,855.

Example 1 Grams Sodium chloride 400 2-(2-hydroxyphenoxy)ethanol 152 Water 4000 The recorder was equipped with an eroding anode electrode made of stainless steel. A mark was obtained which diffused into the paper.

Example 2 Grams Sodium chloride 400 Pyrogallol-l-methyl ether 80 Water 4000 The recorder was equipped with an eroding anode electrode as in Example 1. A mark was obtained which diffused into the paper, the mark being darker on the cathode side as both an eroding and a non-eroding mark was present.

Example 3 Paper impregnated with the formulation of Example 2 was used in a recorder equipped with a platinum noneroding anode electrode. A mark was obtained on the cathode side of the paper.

Example 4 Grams Sodium chloride 400 2-(2,3-dihydroxyphenoxy)ethanol 100 Water 4000 The recorder was equipped with an eroding anode electrode as in Example 2 and a similar mark was obtained as in Example 2.

Example 5 Paper impregnated with the formulation of Example 4 was used with a non-eroding anode electrode. A cathode mark was formed.

Formulations were made including additions for improved stabilization, anti-fringing action etc. as follows:

Example 8 Grams Potassium nitrate 400 2-(Z-hydroxyphenoxy)ethanol 152 Oxalic acid 5 Thiourea 10 Water 4000 Example 9 Grams Sodium chloride 400 2- 2-hydroxyphenoxy) ethanol 270 T hiourea 7 Oxalic acid 3 Water 4000 The formulations of Examples 6 and 7 produced marks in both eroding and non-eroding anode electrode recording systems. The formulations of Examples 8 and 9 produced marks with an eroding metal anode electrode. The formulations of Examples 6 through 9 were found to be capable of longer storage periods without discoloration both before and after marking and the quality of the mark was generally improved over that obtained in the case of Examples 1 and 4.

In any of the above formulations instead of the polyhydric phenol ether named any other member of the class may be substituted for use with an eroding anode electrode. In the event a non-eroding anode electrode is used the substitution must be made from the subclass set out hereinbefore.

Salts may be used when needed in order to provide an electrolytically conducting solution as is known in the art. Preferred salts may be selected from the group including chlorides, bromides, nitrates, sulphates of sodium, potassium, lithium, magnesium, rubidium, and cesium. The quantity of such salt may be varied from a minimal amount up to its solubility limit to give the desired conductivity.

The quantities of the marking compound may be varied from a minimal amount up to the solubility limit thereof. Solubilizers, as known in the art, may be included to afford increased solubility and the term solubility limit as used herein contemplates the extension afforded by the use of such additions.

In order to reduce air oxidation of the marking compound during storage stabilizers such as 'thiourea, alkyl derivatives of thiourea, dithiobiuret, and other known stabilizers may be included in the formulations. The stabilizers may be varied from a minimal amount up to the solubility limit thereof taking into consideration that a stabilizer to some extent may limit the density of the recorded mark.

The impregnant in any of the above formulations may also include an acidifier such as sulphruic acid, nitric acid, and hydrochloric acid. Also one or more anti-fringing agents, some of which also function as acidifiers, such as citric, oxalic, phosphoric, tartaric, and formic acids and salts thereof may be included. In all cases it is desirable that the impregnated medium have a pH in the range of 1 to 5 and preferably about 2.0 inasmuch as the stability of the marking medium is thereby enhanced.

As used herein, the term impregnant is intended to mean a solution which contains an electrolyte, at least one phenolic ether, and which also may contain other additives such as antifringing agents and stabilizers.

The drawing shows typical recording response curves made at a resolution of lines per inch, and a spot size of the order of .0001 square inch at various recording spot speeds for both eroding and non-eroding recording systems. The ordinate is optical density in arbitrary units and the abscissa is current in milli-amperes. The spot speeds were respectively, for curve #1, 23 inches per second, for curve #2, 45 inches per second, and for curve #3, inches per second.

FIGURE 1 shows typical recording response curves of paper impregnated according to Example 6 using pyrogallol-methyl ether as the marking compound in a recorder equipped with an eroding anode electrode.

FIGURE 2 shows typical recording response curves of paper impregnated according to Example 6 in a recorder equipped with a non-eroding anode electrode. FIGURE 3 shows typical recording response curves of paper impregnated according to Example 8 using 2-(2- hydroxyphenoxy)ethanol as the marking compound in a recorder equipped with an eroding anode electrode.

It will be noted that the curves obtained for both the eroding and non-eroding marking systems are comparable to those obtained through use of marking formulations known to the art.

While the invention has been described with reference to specific embodiments thereof, it will be understood that other embodiments maybe resorted to without departing from the invention. Therefore, the form of the invention set out above should be considered as illustrative and not as limiting the scope of the following claims.

We claim:

1. An electrolytic recording medium comprising an impregnated sheet containing in an electrolytically conducting solution as a marking compound a phenolic ether selected from the class consisting of R OH where R R R and R are selected from the group consisting of H, lower aliphatic hydrocarbon groups usually having one to six carbon atoms, OH, -OR (where R is a lower aliphatic group usually having one to six carbon atoms); where M is selected from the group consisting of aliphatic, cycloaliphatic, aromatic, and heterocyclic groups, but usually aliphatic groups.

2. An electrolytic recording medium comprising an impregnated sheet containing in an electrolytically conducting solution as a marking compound a phenolic ether selected from the class consisting of:

2- (Z-hydroxyphenoxy) ethanol 2,3-dihydroxyphenoxy acetic acid 2,6-dihydroxyphenoxy acetic acid 2,3-dihydroxyphenoxy beta propionic acid pyrogallol-l-methyl ether pyrogallol-Z-methyl ether 2,6-dimethoxyphenol pyrogallol-I-(Z-hydroXyethyDether pyrogallol-Z(2-hydroxyethyl)ether pyrogallol-l-allyl ether pyrogallol-Z-allyl ether 3-methoxy-6-methyl-l,Z-dihydroxy benzene 3-(2,3-dihydroxyphenoxy)n-propyl amine 2,6-dihydroxy-3 allyl) phenoxyallyl ether 2-methoxy-1,4 dihydroxy benzene 2-(2,3-dihydroxyphenoxy)ethanol.

3. An electrolytic recording medium according to claim 1 in which an acidifier is present.

4. An electroilytic recording medium according to claim 1 in which the solution contains at least one compound selected from the group consisting of sulphuric acid, nitric acid, hydrochloric acid, citric acid and salts thereof, oxalic acid and salts thereof, phosphoric acid and salts thereof, tartaric acid and salts thereof, and formic acid and salts thereof.

5. An electrolytic recording medium according to claim 1 in which the pH of the impregnated medium is in the range of 1.0 to 5.0.

6. An electrolytic recording medium according to claim 4 in which a stabilizer is present.

7. An electrolytic recording medium according to claim -1 in which a stabilizer is incorporated and is selected from the group consisting of thiourea, alkyl derivatives of thiourea, and dithiobiuret.

8. An electrolytic recording medium according to claim 1 in which a salt is present.

9. An electrolytic recording medium according to claim 1 in which the electrolyte is selected from the group consisting of chlorides, bromides, nitrates, sulphates of sodium, potassium, lithium, magnesium, rubidium, and cesium.

10. An electrolytic recording medium according to claim 1 in which the impregnant consists essentially in approximate parts by relative weights of marking compound 20, electrolyte 100, and stabilizer 1.

11. An electrolytic recording medium comprising an impregnated sheet containing in an electrolytically conducting solution as a marking compound a polyhydric phenol ether selected from the class consisting of o-M R- OH 1'1 where R, R and R are selected from the group consisting of H, lower aliphatic hydrocarbon groups usually having one to six carbon atoms, -OH, -OR (where R is a lower aliphatic group usually having one to six carbon atoms); where M is selected from the group consisting of aliphatic, cycloaliphatic, aromatic, and heterocyclic 0 groups, but usually aliphatic groups.

12. An electrolytic recording medium according to claim 11 in which the polyhydric phenol ether is selected from the class consisting of:

pyrogallol-l-methyl ether pyrogallol-li-allyl ether 3methoxy-6-methyl-1,2-dihydroxy benzene Z-methoxy-lA-dihydroxy benzene 2-(2,3-dihydroxyphenoxy)ethanol.

13. An electrolytic recording medium comprising a paper support impregnated with a solution including water, a salt, a stabilizer, and acid, and 2-(2-hydroxyphenoxy)- ethanol as a marking compound.

14. An electrolytic recording medium comprising a paper support impregnated with a solution including water, a salt, a stabilizer, an acid, and pyrogallol-l-methyl ether as a marking compound.

15. An electrolytic recording medium comprising a paper support impregnated with a solution including water, a salt selected from the group consisting of the alkali metal chlorides and nitrates in quantities ranging from a minimal amount up to the solubility limit thereof, a stabilizer selected from the group consisting of thiourea, alkyl derivatives of thiourea, and dithiobiuret in quantities ranging from a minimal amount up to the solubility limit thereof, an acid selected from the group consisting of sulphuric, nitric, hydrochloric, citric, oxalic phosphoric, tartaric, and formic in quantities suflicient to produce a pH of the impregnant solution in the range of 1.0 to 5.0, and as a marking compound a polyhydric phenol ether selected from the class consisting of R OH where R, R and R are selected from the group con- 7 sisting of H, lower aliphatic hydrocarbon groups usually having one to six carbon atoms, -OH, -OR (where R is a lower aliphatic group usually having one to six carbon atoms); where M is selected from the group consisting of aliphatic, cycloaliphatic, aromatic, and heterocyclic groups, but usually aliphatic groups.

16. An electrolytic recording medium comprising a paper support impregnated with a solution including water, a salt selected from the group consisting of the alkali metal chlorides and nitrates in quantities ranging from a minimal amount up to the solubility limit thereof, a stabilizer selected from the group consisting of thiourea, alkyl derivatives of thiourea, and dithiobiuret in quantities ranging from a minimal amount up to the solubility limit thereof, an acid selected from the group consisting of sulphuric, nitric, hydrochloric, citric, oxalic, phosphoric, tartaric, and formic in quantities sufiicient to produce a pH of the impregnant solution in the range of 1.0 to 5.0, and as a marking compound 2-(2-hydroxyphenoxy)ethanol in quantity ranging from a minimal amount up to the solubility limit thereof.

17. An electrolytic recording medium comprising a paper support impregnated with a solution including water, a salt selected from the group consisting of the alkali metal chlorides and nitrates in quantities ranging from a minimal amount up to the solubility limit thereof, a stabilizer selected from the group consisting of thiourea, alkyl derivatives of thiourea, and dithiobiuret in quantities ranging from a minimal amount up to the solubility limit thereof, an acid selected from the group consisting 8 of sulphuric, nitric, hydrochloric, citric, oxalic, phosphoric, tartaric, and formic in quantities suflicient to produce a pH of the impregnant solution in the range of 1.0 to 5.0, and as a marking compound pyrogallol-la-methyl ether in quantity ranging from a minimal amount up to the solubility limit thereof.

18. An electrolytic recording medium comprising a paper support impregnated with a solution including in approximate parts by relative weight water 800, potassium nitrate as salt 80, thiourea as stabilizer 2, oxalic acid 1, and 2-(2-hydroxyphenoxy)ethanol 30 as a marking compound.

19. An electrolytic recording medium comprising a paper support impregnated with a solution including in approximate parts by relative weights water 1250, sodium chloride as salt 125, thiourea as stabilizer 1.25, citric acid 1, and pyrogallol-l-methyl ether 25 as a marking compound.

References Cited UNITED STATES PATENTS 2,459,521 1/1949 Greig 204-2 2,513,238 1/1950 Greig 204-2 2,949,409 8/ 1960 Richards 2042 3,024,173 3/1962 Mandel 2042 3,123,542 3/1964 Mandel et al. 2042 JOHN H. MACK, Primary Examiner.

W. VAN SISE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,341,431 September 12, 1967 Marcel A. Gradsten et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 18, for "3,358,839 read 2,358,839 line 64, for "pharmaceutic" read pharmaceutical column 2, lines 5 to 9, at the lower left-hand side of the formula reading R read R line 16, for "aliphatc" read aliphatic line 49, for "Vincinal" read vicinal same line 49, for "hydroxy" read hydroxyl lines 53 to 59, at the lower left-hand side of the formula reading R read R same column 2, lines 62 and 64, for "alphatic", each occurrence, read aliphatic column 4, line 54, for "sulphruic" read sulphuric column 5, line 55, for "pyrogallol2(2-hydrox yethyl)ether" read pyrogallol-2(2hydroxyethyl)ether line 65, for "electroilytic" read electrolytic column 6, line 2, for the claim reference numeral "4" read l Signed and sealed this 19th day of November 1968.

( E Attest:

EDWARD M.FLETCHER,JR. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. AN ELECTROLYTIC RECOIRDING MEDIUM COMPRISING AN IMPREGNATED SHEET CONTAINING IN AN ELECTROLYTICALLY CONDUCTING SOLUTION AS A MARKING COMPOUND A PHENOLIC ETHER SELECTED FROM THE CLASS CONSISTING OF 